1. Field of the Invention
This invention relates to a method and apparatus for rotating a cylindrical drum. More particularly, this invention relates to rotating a cylindrical drum using a plurality of hydraulic ram drives.
2. The Prior Art
Ram drives for translating lateral motion to rotational motion are known for use in slowly rotating objects. For example, U.S. Pat. No. 3,915,064, issued to Dancs, the specification for which is incorporated herein by reference, shows a fluid drive device for high torque, low speed applications. Such drives have the advantage of using inexpensive off-the-shelf hydraulic rams to provide motive force to rotatable objects.
Ram drives in the prior art, however, have a disadvantage in that they concentrate a high degree of torque at one location, usually close to an axle used to rotate the drum. If the torque is concentrated at an axle, the axle and the connection of the axle to the drum must be constructed of a material that not only can withstand the loading of the drum on the axle, but that can withstand the high amount of torque applied to the axle. Furthermore, the drum itself must be constructed of materials that will withstand and distribute the torque imparted onto the drum by the drive. Such materials add considerable cost to the drum.